The content of docs/_docs/usage/coverage.md is not at the right place

[julienrf]

I think the website https://dotty.epfl.ch should host the “nightly” documentation (as opposed to the website https://docs.scala-lang.org, which contains the documentation for the latest stable release of the compiler). Furthermore, https://dotty.epfl.ch should only contain the sections “reference”, “api”, and “internals”. Documentation directed to end-users should go to https://docs.scala-lang.org.

With this in mind, I believe that the file docs/_docs/usage/coverage.md is not at the right place. It covers multiple aspects of code coverage, which should be put in the following places:

• Usage instructions should be put in the documentation of sbt-scoverage,
• The compiler option -coverage-out could be mentioned in the compiler options migration (it seems that we don’t have an equivalent of this page for Scala 3),
• The documentation about the internals should go to the dotty internal documentation (under docs/_docs/internal).

Originally posted by @julienrf in #15099 (comment)